On the one hand, maybe it drains remote suns just like how it destroys remote planets. But in that case, why does it drain its own sun? On the other hand, maybe it does move around to new suns, but in that case why doesn’t it completely drain the first sun it orbits like it does the second (Hux’s speech is in daylight)? To me it doesn’t matter much either way.

I honestly never thought it was two different stars. I just figured the star that they drained to destroy the Hosnian system was large enough that they were able to get two charges out of it.

But Finn claims that the weapon draws power from the sun until it disappears, implying that once the draining starts, it will not stop until the star is destroyed. Poe repeats this during their attack.

Stop and think for a moment. Using up two stars does not mean it had to move. It is possible that they found the ideal system with multiple stars to use with this weapons. They probably destroyed the smallest star first and from a larger one they might get several charges out of it. There is a big difference between Sol and Sirius. A star that might give one charge could be the companion of a star that can give sixty. And I never got the impression that the first star was destroyed as Starkiller base never went dark which it would if the sun was sucked dry. Sometimes science can be the friend of wild SF storytelling.

You keep mentioning how the sky never went dark, but… I thought we only saw it charge once? It was charged at some point off screen (same system or a different one? The film doesn’t answer this question and it’s really irrelevant. It could’ve been charged before the movie even started for all we know). It expends this charge when it fires on the Hosnian system. Then it begins draining the star that it currently orbits in order to fire on the resistance.

So, of course the sky never went dark. We only actually SAW it charging once, after it had fired.

Are you suggesting that it only somewhat drains the sun, and after a bit the sun builds back its energy so that it’s not dark anymore?

What? No. I have no idea what’s going on with this discussion anymore.

My point was this:

SKB charges up off screen by sucking up some other star. This probably happened before we ever saw SKB and it had already moved to another star while holding on to its charge. It fires on the Hosnian system. It then begins draining the star it’s currently orbiting in order to fire on the resistance. We only see the sky go dark during the final battle because that is the only charging cycle we actually see on screen.

I don’t remember if there’s any dialogue or something else in the film that might contradict this scenario. But this certainly seems like the most likely sequence of events to me.